Automatic Updates
This example uses the LineSeries
class but it works the same for any series in the library
View model
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LiveChartsCore;
using LiveChartsCore.Defaults;
using LiveChartsCore.SkiaSharpView;
namespace ViewModelsSamples.Lines.AutoUpdate;
public partial class ViewModel : ObservableObject
{
private readonly Random _random = new();
private readonly ObservableCollection<ObservableValue> _observableValues;
public ViewModel()
{
// Use ObservableCollections to let the chart listen for changes (or any INotifyCollectionChanged). // mark
_observableValues = new ObservableCollection<ObservableValue>
{
// Use the ObservableValue or ObservablePoint types to let the chart listen for property changes // mark
// or use any INotifyPropertyChanged implementation // mark
new ObservableValue(2),
new(5), // the ObservableValue type is redundant and inferred by the compiler (C# 9 and above)
new(4),
new(5),
new(2),
new(6),
new(6),
new(6),
new(4),
new(2),
new(3),
new(4),
new(3)
};
Series = new ObservableCollection<ISeries>
{
new LineSeries<ObservableValue>
{
Values = _observableValues,
Fill = null
}
};
// in the following sample notice that the type int does not implement INotifyPropertyChanged
// and our Series.Values property is of type List<T>
// List<T> does not implement INotifyCollectionChanged
// this means the following series is not listening for changes.
// Series.Add(new ColumnSeries<int> { Values = new List<int> { 2, 4, 6, 1, 7, -2 } }); // mark
}
public ObservableCollection<ISeries> Series { get; set; }
[RelayCommand]
public void AddItem()
{
var randomValue = _random.Next(1, 10);
_observableValues.Add(new(randomValue));
}
[RelayCommand]
public void RemoveItem()
{
if (_observableValues.Count == 0) return;
_observableValues.RemoveAt(0);
}
[RelayCommand]
public void UpdateItem()
{
var randomValue = _random.Next(1, 10);
// we grab the last instance in our collection
var lastInstance = _observableValues[_observableValues.Count - 1];
// finally modify the value property and the chart is updated!
lastInstance.Value = randomValue;
}
[RelayCommand]
public void ReplaceItem()
{
var randomValue = _random.Next(1, 10);
var randomIndex = _random.Next(0, _observableValues.Count - 1);
_observableValues[randomIndex] = new(randomValue);
}
[RelayCommand]
public void AddSeries()
{
// for this sample only 5 series are supported.
if (Series.Count == 5) return;
Series.Add(
new LineSeries<int>
{
Values = new List<int>
{
_random.Next(0, 10),
_random.Next(0, 10),
_random.Next(0, 10)
}
});
}
[RelayCommand]
public void RemoveSeries()
{
if (Series.Count == 1) return;
Series.RemoveAt(Series.Count - 1);
}
}
Form code behind
using System.Threading.Tasks;
using System.Windows.Forms;
using LiveChartsCore.SkiaSharpView.WinForms;
using ViewModelsSamples.Lines.AutoUpdate;
namespace WinFormsSample.Lines.AutoUpdate;
public partial class View : UserControl
{
private readonly CartesianChart _cartesianChart;
private readonly ViewModel _viewModel;
private bool? _isStreaming = false;
public View()
{
InitializeComponent();
Size = new System.Drawing.Size(100, 100);
_viewModel = new ViewModel();
_cartesianChart = new CartesianChart
{
Series = _viewModel.Series,
// out of livecharts properties...
Location = new System.Drawing.Point(0, 50),
Size = new System.Drawing.Size(100, 50),
Anchor = AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top | AnchorStyles.Bottom
};
Controls.Add(_cartesianChart);
var b1 = new Button { Text = "Add item", Location = new System.Drawing.Point(0, 0) };
b1.Click += (object sender, System.EventArgs e) => _viewModel.AddItem();
Controls.Add(b1);
var b2 = new Button { Text = "Replace item", Location = new System.Drawing.Point(80, 0) };
b2.Click += (object sender, System.EventArgs e) => _viewModel.ReplaceItem();
Controls.Add(b2);
var b3 = new Button { Text = "Remove item", Location = new System.Drawing.Point(160, 0) };
b3.Click += (object sender, System.EventArgs e) => _viewModel.RemoveItem();
Controls.Add(b3);
var b4 = new Button { Text = "Add series", Location = new System.Drawing.Point(240, 0) };
b4.Click += (object sender, System.EventArgs e) => _viewModel.AddSeries();
Controls.Add(b4);
var b5 = new Button { Text = "Remove series", Location = new System.Drawing.Point(320, 0) };
b5.Click += (object sender, System.EventArgs e) => _viewModel.RemoveSeries();
Controls.Add(b5);
var b6 = new Button { Text = "Constant changes", Location = new System.Drawing.Point(400, 0) };
b6.Click += OnConstantChangesClick;
Controls.Add(b6);
}
private async void OnConstantChangesClick(object sender, System.EventArgs e)
{
_isStreaming = _isStreaming is null ? true : !_isStreaming;
while (_isStreaming.Value)
{
_viewModel.RemoveItem();
_viewModel.AddItem();
await Task.Delay(1000);
}
}
private void B1_Click(object sender, System.EventArgs e)
{
throw new System.NotImplementedException();
}
}